Tumor necrosis factor (TNF) is a pleiotropic cytokine and a central mediator of inflammation. Elevated levels of TNF are associated with various inflammatory diseases including rheumatoid arthritis, psoriasis, and Crohn's disease. Several TNF-neutralizing reagents have been approved for the treatment of these diseases, including soluble TNF receptors (etanercept) as well as anti-TNF antibodies (infliximab, adalimumab, certolizumab pegol, golimumab), and many more are under development. With over 1 million patients treated with TNF antagonists, therapeutic efficacy is well documented. However, global TNF inhibition over a prolonged period of time increases the risk of tuberculosis reactivation, serious infections and even malignancies. Consequently, medical information of all approved anti-TNF medicines includes extensive warnings and precautions.
Two TNF receptors (CD120a, TNFR1 and CD120b, TNFR2) mediate signal transduction upon binding of TNF (Locksley et al. Cell. 2001 Feb. 23; 104(4):487-501). Pro-inflammatory responses are mainly mediated by the ubiquitously expressed TNFR1. TNFR1 is activated both by the membrane-bound form of TNF (mTNF) and soluble TNF (sTNF), which is produced from mTNF by proteolytic cleavage. In contrast, TNFR2, expressed in a more restricted manner e.g. by immune cells, endothelial cells and neurons, can only be activated by mTNF. Activation of TNFR2 mainly induces anti-apoptotic signals and can lead to cell proliferation in vitro. Furthermore, TNFR2 appears to play a role in tissue homeostasis and regeneration.
Selective inhibition of TNFR1 signaling has gained increasing attention as alternative to global TNF neutralization, which affects both TNF receptors. Recently, a TNF mutein (R1antTNF) selectively neutralizing the activity of TNFR1 has been described (Shibata et al. Cytokine. 2008 November; 44(2):229-33. Epub 2008 Sep. 23). This TNF mutein, administered either as unmodified or as PEGylated protein (PEG-R1antTNF), demonstrated therapeutic efficacy in acute murine hepatitis models and a murine collagen-induced arthritis model. The beneficial effect of selectively inhibiting TNFR1 was further supported by results from a dominant-negative TNF mutein (XPro1595), which is capable of forming inactive complexes with sTNF, thus selectively inhibiting the pro-inflammatory action mediated by TNFR1 while preserving the innate immunity to infections (Olleros et al. J Infect Dis. 2009 Apr. 1; 199(7): 1053-63).
TNFR1-selective inhibition can be also achieved with TNFR1-specific antibodies. For example, a monoclonal murine antibody, H398, and antibody described in U.S. Pat. No. 5,736,138, with selectivity for human TNFR1, showed potent inhibition of TNF-mediated signal transduction and cytotoxicity (Moosmayer et al. Ther Immunol. 1995 February; 2(1):31-40).
A humanized version of H398 is described by WO2008/113515A2. Specifically a humanized antibody was produced as Fab fragment (IZI-06.1) and exhibited in vitro neutralizing activities comparable to that of the Fab fragment of the parental antibody. Importantly, the H398 antibody did not reach complete block of TNF activity, which was interpreted by the conversion from an antagonist into a partial agonist at high concentrations. This is explained by dose dependent increase in TNFR1 crosslinking, thus potentially forming ligand independent, functional TNFR1 signalling complexes. Thus, the monovalent Fab was found to be superior over the full length (divalent) antibody because of complete lack of TNFR1 crosslinking capability, thereby avoiding any intrinsic signalling potential.
Antibodies to TNFR1 were found to have an agonistic potential by inducing a response mimicking the ligand. This response suggests that signal transduction is initiated by aggregation of receptors by binding of the multivalent TNF trimers.
Espevik et al (J. Exp. Med. 1990, 171:415-426) describe the agonistic TNFR1 receptor antibody htr-9, which is a full-length antibody found to mimic TNFalpha action.
WO2010094720 describes anti-TNFR1 single domain antibodies (dAbs) and constructs comprising such single domain antibodies.
Brocks et al. (Immunotechnology 3(3) 173-184 (1997)) describe TNF receptor antagonistic mono- and bivalent scFv derivatives.
WO2008113515 describes the anti-TNFR1 antibody H398 and humanized Fab and scFv derivatives thereof.
Armour et al. (European Journal of Immunology 29(8) 2613-2624 (1999)) describe recombinant human IgG1 molecules with mutations to reduce binding to FcgammaRI.
pFUSE-Fc plasmids of InvivoGen (San Diego, Calif., USA) are provided for different applications, e.g. for therapeutic use without cell depletion activity (InvivoGen: “IgG-Fc engineering for therapeutic use” 2007, p. 1-2, XP002616317)
Divalent anti-TNFR1 antibodies were known to bear the risk of pro-inflammatory reactions, including cytotoxicity and apoptosis, which would be contraproductive in treating TNF mediated disease conditions. Monovalent antibody fragments, like scFv, dAb or Fab typically have a short half-life and are therefore of limited use as a pharmaceutical. It was thus the objective to provide an improved anti-TNFR1 agent which would have a prolonged half-life, but avoiding any side effects caused by a TNF agonistic activity.
The object is solved by the subject matter as claimed.